Exercise devices which may be used to stretch scarred joints are well known to those skilled in the art.
By way of illustration, in 1961 Anthony Fuchs disclosed an exercising device which could be used for stretching a knee joint. In his U.S. Pat. No. 3,000,632, Fuchs disclosed a device comprised of a chair with a seat, a horizontally disposed transverse rod mounted adjacent to the seat, and a laterally extending rigid arm. The device of Fuchs appears to be relatively bulky, heavy, complicated, and expensive.
In 1978 Guido Koch disclosed a knee bending device in his U.S. Pat. No. 4,114,610. The device of this patent also is relatively bulky heavy, complicated, and expensive; it is comprised of a chair including a back support and arm rests, a hand-actuated, U-shaped, pivotally mounted stirrup with two substantially parallel limbs, and a connecting central bar.
In 1984, in his U.S. Pat. No. 4,463,947, Arthur Kloenne disclosed a knee and leg orthopedic exercising device The device of the Kloenne patent allegedly is ". . . capable of different degrees of participation or activity, depending upon the condition of the user (see column 1)." However, like the prior art devices discussed above, Kloenne's device is also rather complicated, bulky, and heavy. It is comprised of a chair, a wide leg rest with a vertical shank portion that is supported from a generally perpendicular crown portion, and a base portion comprised of roller means.
In 1985, in his U.S. Pat. No. 4,509,509, a reciprocating apparatus for treating human joints was disclosed by Jean Bouvet et al. This apparatus included an electrical stimulator, an electrically-actuated switch device, a control circuit, a pair of limit switches, a hydraulic cylinder, a base, roller means, and means for supporting one leg. In the operation of the rather complex device of this patent, once current flows to the device, a solenoid is activated, and a piston is caused to move within an air cylinder, thereby causing movement of the support means on which the patient's leg is mounted.
In 1986, in their U.S. Pat. No. 4,599,996, Nancy Seith and Robert C. Johnson disclosed an adjustable limb manipulating device. The device of this patent is comprised of a base adapted to be supported on the thigh of a patient's limb, an elongated extensible and retractable lever pivoted to the base, and a extensible and retractable lifter member having a stirrup portion. The device of this patent allows only a limited range of motion, does not provide any mechanical advantage to the user, and is not suitable for use by invalids who often do not possess a great deal of strength.
In 1987, in his U.S. Pat. No. 4,637,379, John H. Saringer disclosed a device for imparting continuous passive motion to a leg joint. The device of this patent contained an elongated base, a foot rest, a first member with a lower pivotal connection to traveling means, a second member, means for latching the first member to the second member, a spacing member, motor means, and control means. The device of this patent is complicated, cumbersome, and costly.
In 1988, in his U.S. Pat. No. 4,784,121, Lester N. Brooks discussed prior art devices which were adapted to articulate, or flex, a knee joint. At column 1 of his patent, Brooks noted that "A further class of exercisers provides upper body assistance, primarily through the user's arms in articulating the knee . . . U.S. Pat. Nos. 2,772,881--Fundom, 3,000,632--Fuchs and 4,114,610--Koch exemplify this class. The Fundom exerciser is relatively complicated. It has a further shortcoming in that flexion of the knee joint is not as fully controlled as would normally be desired. The Fuchs and Koch exercisers are incorporated into the structure of a chair . . . Although these devices provided the desired end of flexing a knee . . . , shortcomings still exist. . . . The prior devices fail to provide a degree of control over leg movement which allows the user to determine the rate and extent of movement consistent with his tolerance to the pain involved, or with his desire to stress the leg muscles (see column 1 of the patent)"
Despite his recognition of the shortcomings of the prior art devices, the device disclosed in Brooks' United States patent also has substantial disadvantages. In the first place, it does not allow for full extension of the user's knee joint. In the second place, it has to be used in conjunction with a chair, thereby preventing the user from fully flexing the knee joint. In the third place, it does not provide mechanical advantage to the user, and thus cannot advantageously be used by invalids who might not possess a substantial amount of strength and endurance.
Another discussion of knee extending devices was presented in Stephen A. Rogers' U.S. Pat. No. 4,884,454 (1989). In this patent, Rogers notes that "A number of devices . . . have been proposed for use in facilitating knee and leg rehabilitation, some of such devices being disclosed in U.S. Pat. Nos. 4,114,610, 3,000,632, 4,463,947, 4,637,379, 4,509,509, and 4,599,996. Although some of the apparatus disclosed in these patents and elsewhere would apparently accomplish the desired knee and leg therapy and rehabilitation, such apparatus typically is also complicated in structure, cumbersome, and costly."
The device of the Rogers patent, notwithstanding Rogers' appreciation of the shortcomings of the prior art, is relatively expensive, fails to provide substantial mechanical advantage to the user, and is relatively cumbersome.
Thus, as least as late as 1989, the prior art did not provide a knee stretching device which (1) allowed for full knee joint flexion, (2) allowed for full knee joint extension, (3) provides a substantial mechanical advantage to the user which may be maintained by him for relatively long periods of time (4) was relatively lightweight, (5) was simple in structure, (6) was easy to use, (7) was relatively inexpensive.
It is an object of this invention to provide a device for stretching a knee joint which may be used in an environment containing a substantial amount of water (such as a whirlpool bath or a sauna) without substantial risk of deterioration of the device.
It is another object of this invention to provide a device for stretching a knee joint which is relatively inexpensive.
It is another object of this invention to provide a device for stretching a knee joint which is relatively lightweight, portable, and easy to use.
It is another object of this invention to provide a device for stretching a knee joint which allows the user to fully extend the knee joint.
It is another object of this invention to provide a device for stretching a knee joint which allows the user to fully flex his knee joint.
It is another object of this invention to provide a device for stretching a knee joint which provides a substantial amount of mechanical advantage to the user so that one may stretch his knee joint to the desired extent for a relatively long period of time.
It is another object of this invention to provide a device for stretching a knee joint which allows the user of the device to control the amount of stretch and, thereby, to minimize the amount of protective muscle guarding of the knee joint which will exist.